Comparative study of volatile flavor compounds in green onion (Allium fistulosum L.) processed with different cooking methods

The characteristic aroma of green onions was effective in masking the fishy smell in dishes and enhancing the overall flavor. The study aimed to isolate and identify the volatile compounds present in raw, boiled, fried, and roasted green onions using gas chromatography-ion migration spectrometry (GC-IMS). The relative odor activity value (ROAV) was determined, and principal component analysis (PCA) was used to analyze the elements. A total of 64 volatile compounds were finally identified from the green onions and classified as sulfur compounds (19 species), aldehydes (14 species), alcohols (12 species), ketones (13 species), esters (5 species), and furans (1 species). The results of fingerprint analysis indicated that the unique flavor of raw green onions could be attributed to sulfur compounds such as allyl methyl trisulfide and diethyl trisulfide. The unique flavor of boiled green onions can be attributed to the presence of aldehydes such as E-2-octenal and E-2-heptenal. The characteristic flavor components of fried green onions were 3-methyl-butanol and 2-methyl-butanol. Roasted green onions contained ketones, including 2-Butanone and 3-Pentanone, which contributed to their unique flavor. The results of the principal component analysis (PCA) indicated that the flavor of boiled and fried green onion was similar, while a significant difference was observed between raw and roasted green onions.